An innate immune response to viral double-stranded RNA (dsRNA) is activated upon binding by sensor dsRNA binding proteins (dsRBPs). However, dsRBP-dependent activation of innate immunity in the absence of pathogen has been observed in some human diseases, suggesting that an unrecognized source of cellular dsRNA is involved. Using the genetically tractable model organism C. elegans, I will investigate this novel function of cellular dsRNAs, wherein changes in cellular dsRNA levels are sensed by dsRBPs and lead to downstream changes in gene expression. In Aim 1, I will identify genes and pathways affected by altered cellular dsRNA levels by comparing gene expression profiles of C. elegans strains in which genes encoding dsRNA are overexpressed or deleted. In Aim 2, I will identify genomic loci encoding cellular dsRNA using high- throughput sequencing of samples coimmunoprecipitated with dsRBPs. Common genomic regulatory elements of dsRNA loci identified using bioinformatics approaches will provide information regarding the regulation and biological function of these dsRNAs. Finally, in Aim 3 I will utilize both genome-wide RNAi screens and targeted genetic studies to identify cellular mechanisms regulating dsRNA expression. These studies will advance our understanding of dsRNA's role in the cell, and furthermore, have the potential to reveal dsRNA as a new target in the treatment of human diseases including cancer.